2 The Gsa/s Arbitrary Waveform Generator Module Design Digital Channels

With the technological development of the instrument bus interface and digitalsampling, signal processing, programmable logic devices. The functions of SignalGenerator are also from simple combination toward to multi-waveform generation,digital and analog signal generation and network operating in one instrument. In a widerang of application, AFG (Arbitrary Function Generator) and AWG (ArbitraryWaveform Generator) to become the dominant instrument in signal generator. Bothcompared, the cost of AFG is low, but its function is limited to the function signalgeneration, less able to provide the multi-waveform; but in theory, AWG can generatearbitrary waveform which from human editors or acquisition by oscilloscope.In this subject, we develop an AWG, which is a peripheral board of a new-stylesynthetic instrument based on PXI-Express specification. The AWG board acceptshigh-speed data from the backplane of synthetic instrument through FPGA PCI-Expresshard core. After the data is cached and rearranged by DDR2-SDRAM, FPGA sends thedata to digital-analog converter AD9739using self-contained high-speed logic resourceOSERDES. Firstly, this paper introduces the scheme of the synthesized instruments, andaccording to this scheme, each module of AWG is designed, including: the ADF4350clock generator circuit, the FPGA logic control module, the high-speed digital to analogconversion circuit of AD9739, DDR2-SDRAM data cache module and boardsynchronization trigger circuit. Secondly, this paper gives a brief analysis of signalintegrity and power integrity in the design of high-speed circuit, then simulates andverifies the high-speed PCB using the Allegro SI simulation software.To verify the control logic code of FPGA, we simulate the logic block withModelsim software and get the FPGA output signal with ChipScope, and then observethe output real-time waveform with oscilloscope and spectrum analyzer. Finally, thispaper shows the2GHz clock signal and arbitrary waveform generated by AD9739.Thetest results meet the scheduled specifications of digital channel of AWG.